Peculiarities in the changes of catecholamine level in the brain, blood, and adrenals of dogs and rats in ontogenesis.

The norepinephrine content of the whole brainstem and of its different parts and the epinephrine and norepinephrine (NE) content in the blood and adrenals in dogs and rats during ontogenesis were studied. The catecholamine (CA) level in the blood and different parts of the dog brainstem increased to the age of 20-30 days and then decreased. The NE value of the whole dog brainstem increased to the age of 9-30 days, and then decreased. The content of NE of the rat brainstem increased to the age of 120 days and then decreased. The amount of CA of the dog and rat adrenals increased progressively from birth to adulthood. The CA brain and adrenal level of dogs during postnatal ontogenesis was lower than in rats.